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Ch.5 - Thermochemistry
Chapter 5, Problem 15a

(a) The electrostatic force (not energy) of attraction between two oppositely charged objects is given by the equation F = k (Q1Q2/d2) where k = 8.99⨉109N-m2/C2, Q1 and Q2 are the charges of the two objects in Coulombs, and d is the distance separating the two objects in meters. What is the electrostatic force of attraction (in Newtons) between an electron and a proton that are separated by 1⨉102 pm?

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Coulomb's Law

Coulomb's Law describes the electrostatic force between two charged objects. It states that the force (F) is directly proportional to the product of the magnitudes of the charges (Q1 and Q2) and inversely proportional to the square of the distance (d) between them. The equation F = k(Q1Q2/d²) quantifies this relationship, where k is the electrostatic constant.
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Units of Charge and Distance

In the context of electrostatics, charge is measured in Coulombs (C), while distance is typically measured in meters (m). The problem involves converting picometers (pm) to meters, as 1 pm equals 1×10⁻¹² m. Understanding these units is crucial for correctly applying Coulomb's Law and calculating the electrostatic force.
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Formal Charge

Electrostatic Force Calculation

To calculate the electrostatic force between an electron and a proton, one must substitute the known values into Coulomb's Law. The charge of an electron is approximately -1.6×10⁻¹⁹ C, and that of a proton is +1.6×10⁻¹⁹ C. By using the distance of 1×10² pm (or 1×10⁻¹⁰ m), one can compute the force in Newtons, which indicates the strength of the attraction between these two fundamental particles.
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